Updated three files: README.md (four crates, added opake-derive bullet), docs/ARCHITECTURE.md (crate tree, identity.json 0600 note, File Permissions section), CONTRIBUTING.md (opake-derive in architecture diagram). Verified no stale 'three crates' references remain.
Updated three files: README.md (four crates, added opake-derive bullet), docs/ARCHITECTURE.md (crate tree, identity.json 0600 note, File Permissions section), CONTRIBUTING.md (opake-derive in architecture diagram). Verified no stale 'three crates' references remain.